ReferenceError: client is not defined

presto-client-node

Distributed query engine "Presto" 's client library for node.js.

var presto = require('presto-client');
var client = new presto.Client({user: 'myname'});

client.execute({
  query:   'SELECT count(*) as cnt FROM tblname WHERE ...',
  catalog: 'hive',
  schema:  'default',
  source:  'nodejs-client',
  state:   function(error, query_id, stats){ console.log({message:"status changed", id:query_id, stats:stats}); },
  columns: function(error, data){ console.log({resultColumns: data}); },
  data:    function(error, data, columns, stats){ console.log(data); },
  success: function(error, stats){},
  error:   function(error){}
});

Installation

npm install -g presto-client

Or add presto-client to your own package.json, and do npm install.

API

new Client(opts)

Instanciate client object and set default configurations.

opts [object]
- host [string]
  - Presto coordinator hostname or address (default: localhost)
- ssl [object]
  - Setting a Hash object enables SSL and verify server certificate with options (default: null):
    - ca: An authority certificate or array of authority certificates to check the remote host against
    - cert: Public x509 certificate to use (default : null)
    - ciphers : Default cipher suite to use. (default: https://nodejs.org/api/tls.html#tls_modifying_the_default_tls_cipher_suite)
    - key: Private key to use for SSL (default: null)
    - passphrase: A string of passphrase for the private key or pfx (default: null)
    - pfx: Certificate, Private key and CA certificates to use for SSL. (default: null).
    - rejectUnauthorized: If not false the server will reject any connection which is not authorized with the list of supplied CAs. This option only has an effect if requestCert is true (default: true)
    - secureProtocol: Optional SSL method to use. The possible values are listed as SSL_METHODS, use the function names as strings. For example, "SSLv3_method" to force SSL version 3 (default: SSLv23_method)
    - servername: Server name for the SNI (Server Name Indication) TLS extension
- port [integer]
  - Presto coordinator port (default: 8080)
- user [string]
  - Username of query (default: process user name)
- source [string]
  - Source of query (default: nodejs-client)
- basic_auth [object]
  - Pass in a user and password to enable Authorization Basic headers on all requests.
  - basic_auth: {user: "user", password: "password"} (default:null)
- custom_auth [string]
  - Sets HTTP Authorization header with the provided string.
  - Throws exception if basic_auth is also given at the same time
- catalog [string]
  - Default catalog name
- schema [string]
  - Default schema name
- checkInterval [integer]
  - Interval milliseconds of each RPC to check query status (default: 800ms)
- enableVerboseStateCallback [boolean]
  - Enable more verbose callback for Presto query states (default: false)
  - When set to true, this flag modifies the condition of the state change callback to return data every checkInterval(default: 800ms). Modify checkInterval if you wish to change the frequency.
  - Otherwise (false), the state change callback will only be called upon a change in state.
  - The purpose of this variable is to enable verbose update capability in state callbacks. This is such that "percentage complete" and "processed rows" may be extracted despite the state still remaining in a particular state eg. "RUNNING".
- jsonParser [object]
  - Custom json parser if required (default: JSON)
- engine [string]
  - Change headers set. Added for compatibility with Trino.
  - Available options: presto, trino (default: presto)
- timeout [integer :optional]
  - The seconds that a query is allowed to run before it starts returning results, defaults to 60 seconds. Set to null or 0 to disable.

return value: client instance object

execute(opts)

This is an API to execute queries. (Using "/v1/statement" HTTP RPC.)

Execute query on Presto cluster, and fetch results.

Attributes of opts [object] are:

query [string]
catalog [string]
schema [string]
timezone [string :optional]
user [string :optional]
prepares [array(string) :optional]
- The array of prepared statements, without PREPARE query0 FROM prefix.
- Prepared queries can be referred as queryN(N: index) like query0, query1 in the query specified as query. Example:
```
client.execute({ query: 'EXECUTE query0 USING 2', prepares: ['SELECT 2 + ?'], /* ... */ });
```
info [boolean :optional]
- fetch query info (execution statistics) for success callback, or not (default false)
headers [object :optional]
- additional headers to be included in the request, check the full list for Trino and Presto engines
timeout [integer :optional]
cancel [function() :optional]
- client stops fetch of query results if this callback returns true
state [function(error, query_id, stats) :optional]
- called when query stats changed
  - stats.state: QUEUED, PLANNING, STARTING, RUNNING, FINISHED, or CANCELED, FAILED
- query_id
  - id string like 20140214_083451_00012_9w6p5
- stats
  - object which contains running query status
columns [function(error, data) :optional]
- called once when columns and its types are found in results
- data
  - array of field info
  - [ { name: "username", type: "varchar" }, { name: "cnt", type: "bigint" } ]
data [function(error, data, columns, stats) :optional]
- called per fetch of query results (may be called 2 or more)
- data
  - array of array of each column
  - [ [ "tagomoris", 1013 ], [ "dain", 2056 ], ... ]
- columns (optional)
  - same as data of columns callback
- stats (optional)
  - runtime statistics object of query
retry [function() :optional]
- called if a request was retried due to server returning 502, 503, or 504
success [function(error, stats, info) :optional]
- called once when all results are fetched (default: value of callback)
error [function(error) :optional]
- callback for errors of query execution (default: value of callback)
callback [function(error, stats) :optional]
- callback for query completion (both of success and fail)
- one of callback or success must be specified
- one of callback or error must be specified

Callbacks order (success query) is: columns -> data (-> data xN) -> success (or callback)

query(query_id, callback)

Get query current status. (Same with 'Raw' of Presto Web in browser.)

query_id [string]
callback [function(error, data)]

kill(query_id, callback)

Stop query immediately.

query_id [string]
callback [function(error) :optional]

nodes(opts, callback)

Get node list of presto cluster and return it.

opts [object :optional]
- specify null, undefined or {} (currently)
callback [function(error,data)]
- error
- data
  - array of node objects

BIGINT value handling

Javascript standard JSON module cannot handle BIGINT values correctly by precision problems.

JSON.parse('{"bigint":1139779449103133602}').bigint //=> 1139779449103133600

If your query puts numeric values in its results and precision is important for that query, you can swap JSON parser with any modules which has parse method.

var JSONbig = require('json-bigint');
JSONbig.parse('{"bigint":1139779449103133602}').bigint.toString() //=> "1139779449103133602"
// set client option
var client = new presto.Client({
  // ...
  jsonParser: JSONbig,
  // ...
});

Development

When working on this library, you can use the included docker-compose.yml file to spin up a Presto and Trino DBs, which can be done with:

docker compose up

Once you see the following messages, you'll be able connect to Presto at http://localhost:18080 and Trino at http://localhost:18081, without username/password:

presto-client-node-trino-1   | 2023-06-02T08:12:37.760Z	INFO	main	io.trino.server.Server	======== SERVER STARTED ========
presto-client-node-presto-1  | 2023-06-02T08:13:29.760Z	INFO	main	com.facebook.presto.server.PrestoServer	======== SERVER STARTED ========

After making a change, you can run the available test suite by doing:

npm run test

Versions

1.1.0:
- add automatic retries for server errors
- follow redirects if servers simply redirect client's request
- fix bug of HTTP/HTTPS procotol handling
- fix bug about cancelling queries
1.0.0:
- add test cases and CI setting, new options and others, thanks to the many contributions from Matthew Peveler (@MasterOdin)
- add "timeout" option to retry requests for server errors
- change "error" callback (or "callback" as fallback path) to be specified when "success" is used
0.13.0:
- add "headers" option on execute() to specify any request headers
0.12.2:
- fix the bug of the "prepares" option
0.12.1:
- add "user" option on execute() to override the user specified per client
0.12.0:
- add X-Trino-Prepared-Statement to support SQL placeholder
- catch Invalid URL errors
0.11.2:
- fix pregression for basic_auth feature
0.11.1:
- fix a critical bug around the code for authorization
0.11.0:
- add "custom_auth" option to specify Authorization header value directly (for Kerberos, OpenID Connect, etc)
0.10.0:
- add "engine" option to execute queries on Trino
0.9.0:
- make "catalog" and "schema" options optional (need to specify those in queries if omitted)
0.8.1:
- fix to specify default ports of http/https if nextUri doesn't have ports
0.8.0:
- fix the bug about SSL/TLS handling if redirections are required
0.7.0:
- support the change of prestodb 0.226 (compatible with others)
0.6.0:
- add X-Presto-Source if "source" specified
0.5.0:
- remove support for execute(arg, callback) using /v1/execute
0.4.0:
- add a parameter to call status callback in verbose
0.3.0:
- add Basic Authentication support
0.2.0:
- add HTTPS support
0.1.3:
- add X-Presto-Time-Zone if "timezone" specified
0.1.2:
- add X-Presto-Session if "session" specified
0.1.1:
- fix bug not to handle HTTP level errors correctly
0.1.0:
- add option to pass customized json parser to handle BIGINT values
- add check for required callbacks of query execution
0.0.6:
- add API to get/delete queries
- add callback state on query execution
0.0.5:
- fix to do error check on query execution
0.0.4:
- send cancel request of canceled query actually
0.0.3:
- simple and immediate query execution support
0.0.2: maintenance release
- add User-Agent header with version
0.0.1: initial release

Todo

node: "failed" node list support
patches welcome!

Author & License

tagomoris
License:
- MIT (see LICENSE)

	if (!opts.success && !opts.callback)
	throw {message: "callback function 'success' (or 'callback') not specified"};

tagomoris / presto-client-node Goto Github PK

presto-client-node's Introduction

presto-client-node

Installation

API

new Client(opts)

execute(opts)

query(query_id, callback)

kill(query_id, callback)

nodes(opts, callback)

BIGINT value handling

Development

Versions

Todo

Author & License

presto-client-node's People

Contributors

Stargazers

Watchers

Forkers

presto-client-node's Issues

Starting 0.161. /v1/execute resource got removed

Has anyone encountered a similar problem?

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